University of Cebu- Main Campus
College of Engineering
Compilation of Problems in
Basic Electrical
Engineering
Submitted to :
Engr. Welhilm Gabut
Submitted by:
Blanche Marie Pueblas
1. If the steady current 2,5 A flows in a wire for 5
minutes, find the charged passed in any point in the
circuit. 750 C
5.
Calculate the heat produced by an electric iron, which
has a resistance of 30 ohms and takes a current of 3
amperes when it is switched on for 15 seconds. 4050
joules
2.
The current in a light bulb is 0.835 A. How long does it
take for a total charge of 1.67 C to pass a point in the
wire? 2sec.
6.
Calculate the resistance of a lamp if a voltage of 12V
causes a current of 3A to flow through the lamp. 4 ohms
(4Ω)
3.
If a battery uses 45J of energy with a charge of 15C
what is the electric potential of the battery? 3 V
7.
Calculate the resistance of a heater if a voltage of 230V
causes a current of 200mA to flow through the heater.
1150 Ω
4.
How many joules of energy are released from a 9V
battery that has a charge of 25C? 225Joules
8.
Calculate the voltage across a resistance of 40Ω when a
current of 5A is flowing. 200V
9.
Calculate the current flowing through a wire of
resistance of 8Ω when a voltage of 12V is connected to
the wire. 1.5A
10. A radiator working with 30V potential difference has
power 180 watt. Find the current passing through and
resistance of the radiator. 6 ampere, 5Ω
13. A d-c generator has an e.m.f of 200 volts and provides a
current of 10 amps. How much energy does it provide
each minute?
14. Calculate the total DC resistance of a 100 metre roll of
2.5mm2 copper wire if the resistivity of copper at 20oC is
1.72 x 10-8 Ω-m. 688 milli-ohms or 0.688 Ohms
11. A 220 V – 5 A electric lamp is used for 30 minutes. How
much energy does it require? 1,980 kiloJoule
15. Calculate the cross-sectional area, in 2 mm , of a piece
of aluminium wire 100 m long and having a resistance of
2. Take the resistivity of aluminium as 0.03 x 10-6 Ω-m.
1.52 mm2
12. If a 40 watt lamp is turned on for one hour, how many
joules of electrical energy have been converted by the
lamp?
16. Find the resistance of 1 km of copper cable having a
diameter of 10 mm if the resistivity of copper 0.017 x
10-6 Ω-m. 0.216 
17. What is the resistance of 1,000 feet of copper wire
having a cross-sectional area of 10,400 circular mils at a
temperature of 20°C? 1 Ω
18. A 12-gauge wire has a diameter of 80.81 mils. What is
(a) its area in circular mils and (b) its area in square
mils?
19. A rectangular conductor is 1.5 inches wide and 0.25 inch
thick. What is (a) its area in square mils and (b) in
circular mils? What size of round conductor is necessary
to carry the same current as the rectangular bar?
20. We have a copper conductor wire with resistance = 20
ohms, at a temperature of 10 °C. What will be the new
resistance value, if it rises to 70°C? 24.85 ohms
21. A length of copper wire (α = 0.004041 at 20o C) has a
resistance of 5 ohms at 20 degrees Celsius. Calculate its
resistance if the temperature were to increase to 50
degrees Celsius.5.606 ohms
22. If the resistance of a copper wire at freezing (0°C) is 30 Ω
, what is its resistance at –40°C? 24.88 ohms
23. If the resistance of a copper wire is 50Ω at 20°C, what is
its resistance at 100°C (boiling point of water)?65.72
ohms
24. If the resistance of a copper wire at freezing (0°C) is 30
Ω, what is its resistance at 40°C?24.88 Ω
25. If the resistance of an aluminum wire at room
temperature (20°C) is 100mΩ, at what temperature will
its resistance increase to 120mΩ? T2=71.2°C
26. An incandescent light bulb has a filament resistance of
5.7 Ω when at room temperature (20o C), but draws
only 225 mA when powered by a 12 volt DC source.
Given that the filament is made out of tungsten metal,
calculate its temperature in degrees F when powered by
the 12 VDC source.3434 °F
27. A copper wire has a diameter of 0.325 in. and a
resistance of 0.6 ohm at 20°C. Calculate its
length.611.38 ft.
28. What kind of material is used in the armature on the
construction of a 39-ohm rheostat if the wire has a
length of 266 ft. and a diameter of 22.6 mils? 75ohmCM/ft.
29. A coil of copper wire has a resistance of 62 ohms at
room temperature of 24°C. (a) What will be its
resistance at 80°C,(b) at -20°C? 75.43 ohms, 51.45
ohms
30. The diameter of a conductor is 0.064 inch. What is
the area in circular mils? 4096 CM
31. A 500 MCM ASCR cable has 37 strands. Determine the
diameter of each strand in mils? 116.247 mils
32. A 400,000 CM cable is compose of 37 strands. What
is diameter, in mils, of each strand? 104 mils
33. A copper bus bar has a rectangular cross section of
dimensions 2 inches by 6 inches.
Determine the
cross section area of bus bar in circular mils.
15.2788x106 CM
37. What length ( in cm) of wire of diameter 0.315 mm will
be required to construct a coil of resistance 10 ohms, if
the specific resistance of the wire is 49μ ohm-cm. 159
cm
34. A bus bar has a cross section of 0.5 inch by 0.6 inch.
Determine its cross sectional area in circular mils.
381,972.86 CM
38. A copper winding has a resistance of 0.25 ohm at a
temp. of 18°C. Calculate the temp. in the winding when
after a period of operation, the resistance increase to
0.31 ohm. 78.6°C
35. The specific resistance of copper used as electric wires
is 10.4 ohm-CM per foot. Find the resistance of 1500 ft.
of copper wire whose diameter of 0.08 inch. 2.437
ohms
39. A coil has resistance of 10 ohms at 15°C. Solve its
resistance at 30°C if the temp. coefficient of resistance
at 0°C is 0005/°C. 10.7 ohms
36. A standard copper wire is 0.0064 inch in diameter.
What is the resistance of 1000 ft. of this wire at 20°C.
2. 53 ohms
40. The copper field winding of an electric machine has a
resistance of 46 ohms at a temp. of 22°C.What will
be its resistance at a temp. of 75°C
41. An electric press has resistance of 80 ohms when cold
(@ 20°C). When hot the resistance rises to 150 ohms.
What temp. is reached if a constant temp. coefficient
of 0.00618 at 0°C is assumed? 179.084°C
45. The value of ao of a conductor is 1/236 per °C. The
value of a18 will be per °C.
42. It is found that the resistance of a coil wire increases
from 50 ohms tat 15°C to 58 ohms at 55°C. Calculate the
temp. coefficient at 0°C of the conductor
material.0.00425/°C
46. Determine the insulation resistance of a single -core
cable of length 3km and having conductor radius
12.5mm,insulation thickness 10mm and specific
resistance of insulation of 5x1012ohm. 156 Mohms
43. A given conductor has a resistance of 50 ohms when
it is temp. is 0°C. Calculate its resistance at 60°C if
the temp. coefficient of resistance of the material at
0°C is 0.0043/°C. 63 ohms
47. A single core cable has a conductor radius of 0.5 cm a an
insulation thickness of 0.3 cm. If the specific resistance
of insulation 5x1014 ohm-cm, solve the insulation
resistance per km of the cable. 374Mohms
44. The value of resistance temp. coefficient of a
conductor at 25°C is 1/255 per °C. Its value at 20°C
will be___. 1/ 250 per °C
48. A single -core has an insulation resistance 495 megaohm per km. If the core diameter is 2.5 cm and the
resistivity of the insulation material is 4.5x1014 ohmcm, solve the thickness of the insulation. 1.25 cm
49. The insulation resistance of a cable of length 10km is
1Mohm. For a length of 100 km of the same cable, the
insulation resistance will be. 0.1Mohm
50. A resistor is coded as Grey, Red, Gold, Gold. Convert this
color code. 8.2Ω, 5%
57. A portable machine requires a force of 200 N to move it.
How much work is done if the machine is moved 20 m
and what average power is utilized if the movement
takes 25 s? 160 Watts
58. A source e.m.f. of 5 V supplies a current of 3 A for 10
minutes. How much energy is provided in this time? 9 kJ
51. A resistor is coded as Yellow, Violet, Black, Gold.
Convert this color code. 47 Ω, 5%
52. A resistor is coded as Orange, Orange, Brown ,Gold.
Convert this color code. 330 Ω, 5%
59. An electric heater consumes 1.8 MJ when connected to
a 250 V supply for 30 minutes. Find the power rating of
the heater and the current taken from the supply. 4 A
53. A resistor is coded as Blue, Grey, Brown, Gold. Convert
this color code. 680 Ω, 5%
54. What are the color bands on a 10 kΩ resistor with a 5%
tolerance? Brown, Black, Orange, Gold
55. What are the color bands on a 100 kΩ resistor with a 5%
tolerance? Brown, Black, Yellow, Gold
56. Generate the color code for the following resistors:
(a) Yellow, Violet, Green, Silver. 4.7M Ω or 4,700,000
Ω, 10%
(b) Orange, White, Red, No Color. 3.9k Ω or 3,900 Ω,
20%
(c) Grey, Red, Green, No Color . 8.2M Ω or 8,200,000
Ω,20%
60. Find the conductance of a conductor of resistance 10
ohms. 0.1 siemens
61. A conductor has a conductance of 50 μS. What is its
resistance? 20 kiloohms
65. 450 J of energy are converted into heat in 1 minute.
What power is dissipated? 7.5 W
62. A force of 2.5 kN is required to lift a load. How much
work is done if the load is lifted through 500 cm? 12.5 kJ
66. A current of 10 A flows through a conductor and 1W is
dissipated. What p.d. exists across the ends of the
conductor? 1 V
63. A force of 4 N moves an object 200 cm in the direction
of the force. What amount of work is done? 8J
64. An e.m.f. of 250 V is connected across a resistance and
the current flowing through the resistance is 4 A. What
is the power developed? 1 kW
67. A battery of e.m.f. 12 V supplies a current of 5 A for 2
minutes. How much energy is supplied in this time7.2 kJ
68. A dc electric motor consumes 36 MJ when connected to
a 250 V supply for 1 hour. Find the power rating of the
motor and the current taken from the supply. 10 kW, 40
A
69. What quantity of electricity is carried by 6.24x10^21
electrons? 1000 C
70. In what time would a current of 1 A transfer a charge of
30 C? 30 s
71. A current of 3 A flows for 5 minutes. What charge is
transferred? 900
72. What force is required to give a mass of 20 kg an
acceleration of 30 m/s^2? 600 N
73. Find the accelerating force when a car having a mass of
1.7 Mg increases its speed with a constant acceleration
of 3 m/s^2. 5.1 kN
74. A force of 40 N accelerates a mass at 5
m/s^2.Determine the mass. 8 kg
75. Determine the force acting downwards on a mass of
1500 g suspended on a string.14.72 N
76. What current must flow if 0.24 coulombs is to be
transferred in 15 ms? 16 A
77. If a current of 10 A flows for four minutes, find the
quantity of electricity transferred. 2400 C
81. A 100 V battery is connected across a resistor and
causes a current of 5 mA to flow. Determine the
resistance of the resistor. If the voltage is now reduced
to 25 V, what will be the new value of the current
flowing? 1.25mA
78. The current flowing through a resistor is 0.8 A when a
p.d. of 20 V is applied. Determine the value of the
resistance. 25 ohms
82. What is the resistance of a coil which draws a current of
200 μA from a 120 V supply? 600 000 ohms or 600
kohms or 0.6 Mohms
79. Determine the p.d. which must be applied to a 2 kohms
resistor in order that a current of 10 mA may flow. 20 V
83. A 100 W electric light bulb is connected to a 250 V
supply. Determine
(a) the current flowing in the bulb >>> 0.4 A
(b) the resistance of the bulb >>> 625 ohms
80. A coil has a current of 50 mA flowing through it when
the applied voltage is 12. What is the resistance of the
coil? 240 ohm
84. An electric kettle has a resistance of 30 . What current
will flow when it is connected to a 240 V supply? Find
also the power rating of the kettle. 1.92 kW >> power
rating of kettle
87. A 12 V battery is connected across a load having a
resistance of 40 . Determine the current flowing in the
load, the power consumed and the energy dissipated in
2 minutes. 0.3 A, 3.6 W, 432 J
85. A current of 5 A flows in the winding of an electric
motor, the resistance of the winding being 100 .
Determine
(a.)the p.d. across the winding, and >>>500V
(b) the power dissipated by the coil>>> 2500 W
or 2.5 kW
88. A source of e.m.f. of 15 V supplies a current of 2 A for
six minutes. How much energy is provided in this time?
10.8 kJ
89. In what time would a current of 10 A transfer a charge
of 50 C? 5 s
86. The hot resistance of a 240 V filament lamp is 960
ohms. Find the current taken by the lamp and its power
rating. 0.25 A, 60 W
90. A current of 6 A flows for 10 minutes. What charge is
transferred? 3600 C
91. The current flowing through a heating element is 5A
when a p.d. of 35 V is applied across it. Find the
resistance of the element. 7ohms
94.
92. A 60 W electric light bulb is connected to a 240 V
supply. Determine
(a) the current flowing in the bulb and >>> 0.25 A
(b) the resistance of the bulb.>>> 960 ohms
95. Determine the resistance of an electric fire which takes
a current of 12 A from a 240 V supply. Find also the
power rating of the fire and the energy used in 20
hrs. 20ohms , 2.88 kW, 57.6 kWh
93. Determine the p.d. which must be applied to a 5 kohms
resistor such that a current of 6 mA may flow. 30 V
The hot resistance of a 250 V filament lamp is 625 .
Determine the current taken by the lamp and its power
rating. 0.4 A, 100 W
96. Determine the power dissipated when a current of 10
mA flows through an appliance having a resistance of 8
kohms. 0.8 W
97. 85.5 J of energy are converted into heat in nine
seconds. What power is dissipated? 9.5 W
101. The resistance of 1.5 km of wire of cross-sectional area
0.17 mm^2 is 150 ohms. Determine the resistivity (in
microohm-m) of the wire. 0.017 microohm-m
98. A current of 4 A flows through a conductor and 10 W is
dissipated. What p.d. exists across the ends of the
conductor? 2.5 V
102. Determine the resistance of 1200 m of copper cable
having a diameter of 12 mm. 0.180 ohm
99. Calculate the resistance of a 2 km length of aluminium
overhead power cable if the cross-sectional area of the
cable is 100 mm^2. Take the resistivity of aluminium to
be 0.03x10^- 6 ohm-m. 0.6 ohms
103. The resistance of a 5 m length of wire is 600 ohms.
Determine
(a) the resistance of an 8 m length of the same wire,
and>>> 960 ohms
(b) the length of the same wire when the resistance is
420 ohms.>>> 3.5 m
100. Calculate the cross-sectional area, in mm^2, of a piece
of copper wire, 40 m in length and having a resistance
of 0.25 . Take the resistivity of copper as 0.02x10^-6
ohm-m. 3.2 mm^2
104. A piece of wire of cross-sectional area 2 mm^2 has a
resistance of 300ohms.
Find (a) the resistance of a wire of the same length and
material if the cross-sectional area is 5 mm^2. 120 ohms
107. A certain unenergized copper transformer winding has a
resistance of 30Ω at 20 °C. Under rated operation,
however, the resistance increases to 35Ω. Find the
temperature of the energized winding. 62.4°C
105.The resistance of a certain copper power line is 100Ω at
20°C. What is its resistance when the sun heats up the
line to 38°C? 107Ω
108. The resistance of a certain aluminum power line is 150
ohms at 20°C. Find the line resistance when the sun
heats up the line to 42°C. First use the inferred zero
resistance temperature formula and then the
temperature coefficient of resistance formula to show
that the two formulas are equivalent. 163 ohms
106. When 120 V is applied across a certain light bulb, a 0.5A current flows, causing the temperature of the
tungsten filament to increase to 2600°C. What is the
resistance of the light bulb at the normal room
temperature of 20°C? 19 ohms
109.Find the resistance at 35°C of an aluminum wire that
has a length of 200 m and a diameter of 1 mm. 7.21
ohms
110.Calculate the temperature coefficient of resistance of
aluminum at 30°C and use it to find the resistance of an
aluminum wire at 70°C if the wire has a resistance of 40
ohms at 30°C. 0.003 759°C-1
111.Calculate the temperature coefficient of resistance of
aluminum at 30°C and use it to find the resistance of an
aluminum wire at 70°C if the wire has a resistance of 40
ohms at 30°C. 46 ohms
115.A 12.1mA current flows through a 10 percent, 2.7-kΩ
resistor. What range must the resistor voltage be in?
29.4 to 35.9 V
116. What are the resistor color codes for tolerances and
nominal resistances of
(a) 10 percent, 0.18 Ω (b) 5 percent, 39 kΩ (c) 20
percent, 20 MΩ?
117. Find the resistance corresponding to color bands in the
order of red-yellow-black-gold. 24Ω with a 5 percent
tolerance
112. What are the colors of the bands on a 10 percent, 5.6 Ω
resistor? green-blue-gold-silver
113.Determine the colors of the bands on a 20
percent,2.7MΩ resistor. red-violet-green-NC
114. What is the resistance range for a 5 percent, 75-kΩ
resistor? 71.25 to 78.75 kΩ
118. Find the tolerances and nominal resistances
corresponding to color codes of
(a) brown-brown-silver-gold (b) green-brown-brownmissing (c) blue-gray-green-silver.
(a) 5 percent, 0.11Ω (b) 20 percent, 510 Ω (c) 10
percent, 6.8 MΩ
119. A voltage of 110 V is across a 5 percent, 20-KΩ resistor.
What range must the current be in? 5.24 mA, 5.79 Ma
124. What is the conductance of a 39 Ω resistor? 25.6 mS
125. What is the conductance of a voltmeter that indicates
150 V when 0.3 mA flows through it? 2μS
120. If the colors on a 6 band resistor is in this order: green,
brown, violet, black, gold and orange.
(a.)517 ohms 15ppm (b) 517ohms 100ppm
(c)517ohms 50ppm (d)517 ohms 5ppm
121. What is the resistance of a 240-V electric clothes dryer
that draws 23.3 A? 10.3ohms
122.If a voltmeter has 500 kΩ of internal resistance, find the
current flow through it when it indicates 86 V.172μA
123. If an ammeter has 2 mΩ of internal resistance, find the
voltage across it when it indicates 10A. 20 mV
126.Find the resistance at 20 C of an annealed copper bus
bar 2 m long and 1 cm by 4 cm in rectangular cross sect
ion. 86 μΩ
127.What is the resistance of an annealed copper wire that
has a length of 500 m and a diameter of0.404 mm?
67.1 μΩ
128.The resistance of a wire is 25Ω . Another wire of the
same material and at the same temperature has a
diameter twice as great and a length six times as great.
Find the resistance of the second wire. 37.5 Ω
129. What is the resistivity of tin if a cube of it 10 cm along
each edge has a resistance of 1.15 μΩ across opposite
faces? 11.5 x 10-8 Ω.m
133. A certain aluminum wire has a resistance of 5Ω at 20°C.
What is the resistance of an annealed copper wire of
the same size and at the same temperature? 3.04 Ω
130.Find the resistance at 20°C of an annealed copper bus
bar 3 m in length and 0.5 cm by 3 cm in rectangular
cross section. 344μΩ
134. A wire 50 m in length and 2 mm2 in cross section has a
resistance of 0.56 Ω. A 100-m length of wire of the same
material has a resistance of 2Ω at the same
temperature. Find the diameter (in mm) of this wire.
1.19mm
131. Finc the resistance of an aluminum wire that has a
length of 1000 m and a diameter of 1.626 mm. The wire
is at 20°C. 13.6Ω
135.A wire-wound resistor is to be made from 0.2-mmdiameter constantan wire wound around a cylinder that
is 1 cm in diameter. How many turns of wire are
required for a resistance of 50 Ω at 20°C? Note: The
number of turns equals the wire length divided by the
circumference of the cylinder. 102turns
132. What is the resistivity of platinum if a cube of it 1 cm
along each edge has a resistance of 10344μΩ across
opposite faces? 10 x 10-8 Ω.m
136.The conductance of a certain wire is 0.5 S. Another wire
of the same material and at the same temperature has a
diameter twice as great and a length three times as
great. What is the conductance of the second wire?
0.667 S
137. Find the conductance of 5 m of nichrome wire that has
a diameter of 1 mm. 157 mS
138. If an aluminum power line has a resistance of 80Ω at
30°C, what is its resistance when cold air lowers its
temperature to -10°C? 68Ω
139. If the resistance of a constantan wire is 2 MΩ at -150°C,
what is its resistance at 200°C? 2.006 MΩ
140. The resistance of an aluminum wire is 2.4 Ω at -5°C. At
what temperature will it be 2.8 Ω? 33.5°C
141.What is the resistance at 90°C of a carbon rod that has a
resistance of 25 Ω at 2O°C? 24.1Ω
142.Find the temperature coefficient of resistance of iron at
20°C if iron has an inferred zero resistance temperature
of -162°C. 0.0055°C -1
143. What is the maximum current that a 1-Watt, 56-kΩ
resistor can safely conduct? 4.23 mA
144. Find the resistance of an electric heater that absorbs
2400 W when connected to a 120-V line. 6Ω
148. What is the resistance of a 240-V, 5600-W electric
heater? Ans. 10.3 Ω
145. Find the internal resistance of a 2-kW water heater that
draws 8.33 A. 28.8Ω
149. A nonlinear resistor has a voltage-current relation of V=
2I2+3I+10. Find the current drawn by this resistor when
37 V is applied across it. 3 A
146. What is the greatest voltage that can be applied across
a 1/8 W, 2.7-M Ω resistor without causing it to
overheat? 581 V
147. What is the maximum voltage that can be safely applied
across a 0.5W, 91 Ω resistor? 6.75 V
150. If a nonlinear resistor has a voltage-current relation of
V= 3I2 + 4, what current does it draw when energized by
61 V? 4.36 A
151. If a nonlinear resistor has a voltage-current relation of
V= 3I2 + 4, what power does it absorb? 266 W
152. At 20°C a pn junction silicon diode has a current-voltage
relation of I = 10- 14(e40V - 1). What is the diode voltage
when the current is 50 mA? 0.73 V
155. A 3-hp automobile electric starter motor operates at 85
percent efficiency from a 12-V battery. What is the
battery internal resistance if the battery terminal
voltage drops to 10 V when energizing the starter
motor? 7.60 mΩ
153. If a diode has a current-voltage relation of I=10- 14(e40V1) is 150 mA? what is the diode voltage when the
current is 150 mA? 0.758 V
156. A short circuit across a current source draws 20 A.
When the current source has an open circuit across it,
the terminal voltage is 600 V. Find the internal
resistance of the source. 30 mΩ
154.A battery provides 6 V on open circuit and it provides
5.4 V when delivering 6 A. What is the internal
resistance of the battery? 0.1 Ω
157. A short circuit across a current source draws 15 A. If a
10Ω resistor across the source draws 13 A, what is the
internal resistance of the source? 65Ω
158. If a 12-V car battery has a 0.14 internal resistance, what
terminal voltage causes a 4-A current to flow into the
positive terminal? 12.4 V
159. If a 10-A current source has a 100-0 internal resistance,
what is the current flow from the source when the
terminal voltage is 200 V? 8A
160.A 90-V source is in series with five resistors having
resistances of 4, 5, 6, 7, and 8Ω . Find the voltage across
the 6Ω resistor. 18V
161. What is the total resistance of 2, 5, 8, 0, and 17Ω
resistors connected in series? 42 Ω
162. What is the total resistance of thirty 6 Ω resistors
connected in series? 180 Ω
163.What is the total conductance of 4, 10, 16, 20, and 24
Siemens resistors connected in series? 1.98 Siemens
164. A 3-V, 300-mA flashlight bulb is to be used as the dial
light in a 120-V radio. What is the resistance of the
resistor that should be connected in series with the
flashlight bulb to limit the current? 390 Ω
165. Resistors R1, R2, and R3, are in series with a 100-V
source. The total voltage drop across R 1, and R2 is 50 V,
and that across R2, and R3, is 80 V. Find the three
resistances if the total resistance is 50Ω. R1= 1OΩ, R2=
15Ω, R3= 25Ω
166. A series circuit consists of 12, 20, and 16 Ω resistors
across of a 240-V source. Find the current out of the
positive terminal of the voltage source. 5A
167.A series circuit consists of 12, 20, and 16Ω resistors
across of a 240-V source. Find the resistor voltages. 60
V, 100 V, 80 V
168. A string of Christmas tree lights consists of eight 6-W,
15-V bulbs connected in series. What current flows
when the string is plugged into a 120-V outlet? 0.4 A
169. A string of Christmas tree lights consists of eight 6-W,
15-V bulbs connected in series. What is the total
resistance of Christmas tree lights ?
170. A resistor in series with an 8- Ω resistor absorbs 100 W
when the two are connected across a 60-V line. Find the
unknown resistance R? 16 Ω, 4 Ω
171. A 12 V battery is connected in a circuit having three
series-connected resistors having resistances of 4 ohms,
9 ohms and 11ohms. Determine the current flowing
through, and the p.d. across the 9 ohms. Find also the
power dissipated in the 11 ohms. 4.5 V, 2.75 W
172.The current flowing in a circuit containing four resistors
connected in series is I = 1A. The potential drops across
the first, second and third resistors are, respectively: V1
= 5V, V2 = 8V and V3 = 7V. The equivalent resistance of
the circuit is R=30 ohms. Find the total voltage supplied
by the battery, and also the total current, voltage drop
V4, and resistance of each resistor in the circuit. 30V,1A,
10V,5 ohms,8 ohms, 7ohms, 10hms
173.A 120 V battery is connected in series with three
resistors: 40 , 60 , and 100 Find the voltage across
each resistor.24V, 36V,60V
174.Two resistors are connected in series across a 24 V
supply and a current of 3 A flows in the circuit. If one of
the resistors has a resistance of 2, determine (a) the
value of the other resistor, and (b) the p.d. across the 2
resistor. If the circuit is connected for 50 hours, how
much energy is used? 6ohms, 3.6 kWh
175.Three resistances of 1 ohm, 2 ohm, and 3 ohm are
connected in series through a potential difference of 12
V. What is the current in each resistance?
I1=2A, I2=2A, I3=2A
176.Three resistors of 3 ohms, 4 ohms, and 6 ohms are
connected in parallel, the combination is connected in
series with a cell of emf 2 volt. What is the total
resistance, current through each resistors and the total
current? 1.333ohms, 0.67A, 0.5A, 0.33A, 1.5A
179.Two resistors, of resistance 3ohms and 6ohms, are
connected in parallel across a battery having a voltage
of 12 V. Determine (a) the total circuit resistance and (b)
the current flowing in the 3 ohms resistor. 2ohms, 4 A
177.If a 6v battery is connected across a 3 ohm resistance,
what is the current flowing in the circuit? 2A
180.Three resistors of 1 ohm, 2 ohms, and 3 ohms, are
connected parallel in a circuit. If 1 ohm resistor draw a
current of 1 ampere, what is the current through the
other two resistors? 0.5A,0.333A
178.A 2 ohm resistor and a 4 ohm resistor are connected in
parallel to a 6 volt battery. The power dissipated by the
2 ohm resistor is? 18 Watts